I am not a native English speaker. I grew up and learnt Bengali in my childhood. I learn Arabic to read the Quran. But I can write and speak fluently in English as well. Not to mention I studied in a school where the medium of teaching was Bangla.
To learn any language, you have to read and hear the words that are spoken. Everytime you hear a word, write it down and look up the meaning in your own language in a dictionary. You can watch English documentary or listen to TV or radio stations. There are no short cuts in learning. Like many books gives you the feeling that you can learn English in 7 or 30 days, are not true.
Learning a language is a lifelong process. It is better to practice with a native English speaker of your choice. Apart from English, you should also learn other languages. For me whenever I find a new word, I try to get the meaning in all three languages that I know. Every language has it’s own beauty and be proud of your mother tounge.
Keep learning new words. Practice hard and practice often. Learning English will let you communicate with a large number of audience and you can also share your knowledge worldwide.